Art of cracking hydrocarbons



Sept. 2, 1930.' E4 W. ISOM ET AL 1,774,601

' ART oF cmcxm HYDRocARBoNs Filed June l1, 1929 ATTORN EYS sure cracking operations.

UNITED STATES EDWARD w. Isoiyr, or scAnsDALn, ANEW Yoan, AND

P AIT EUGENE c. HERTHEL, or CHICAGO,

ILLINOIS, .ASSIGNORS TO SINCLAIR -REEINNG COMPANY, OF NEW YORK, N. Y.,'A

CORPOQRATION 0F MAINE ABT OF (TRACKING: HYDROCARIBONS Application led June 11,

lthe manufacture of lower boiling hydrocarbon oils, such as gasoline, from higher boiling hydrocarbon oils, such as gas oil, by pres- The present invention provides a combined operation including a novel heating operation o1' special value and application in conjunction with operations in which high boiling oil 10 is heated to a cracking temperature under high pressure and in which the hot oil products of this heating operation are separated -into a vaporized fraction and an unvaporized fraction under -lower pressure, or so-called pressure coil cracking operations. A

The invention will be described in connection with the accompanying drawings which illustrate, diagrammatically and conventionally, apparatus embodying and for carrying out the invention. In the accompanying drawings, Fig. l represents,in elevation and partly in section and with parts broken away, apparatus embodying and adapted for carrying out the invention, Fig.2 is a fragmentarysection through and just above the l-ower ends of the heating tubes illustrated in Fig. 1, and Fig. 3 is a fragmentary section similar to Fig. 2 illustrating a modified arrangement of the heating tubes. 1 y

Referring to the drawings, a stream of high boiling oil is forced, by means of pump 2, suc'- cessively through two batteries of series connected vertical heating tubes arranged in a vertical heating flue in heating furnace l, then through a pressure reducing valve 3, and

of which banks consists of a plura ity of series t connected heating tubes. These several banks of heating tubes are arranged transversely to the general direction of travel ofthe heating gases entering the upper end of tht vertical heating iue in which these banks of heating tubes are arranged so that the heating gases entering the upper end of the heat- This invention relates to improvementsin- 1929. Serial No. 370,097.

ing flue fiow across the several banks of heating tubes in succession, first across the banks oI" hea ting tubescomprising the battery 5 and then across the banks of heating tubes comprising the battery 6. rlhe heating gases `entering the upper end of the verticalv heating fine 7 through passage 8 from the iirebox 9, in which fuel is burned for supplying heat to the operation, and after passing across and A back and across the heating tubes while fiowing generally downwardly through the heating flue 7 escape through stack flue 10. The oil flowing through each bank of heating tubes flows successively .upwardly and down- Wardly through the series connected heating -tubes forming the bank.l The oil supplied to the two batteries of heating tubes, through connection ll, flows first through battery 5 and then through battery 6, being discharged through` connection l2. Thus, the heating gases from the firebox 9 pass across the upper end of the heating flue 7 as they enter it through passage 8, passing first over the heating tubes comprising the battery 5 through which the oil supplied to the two batteries of heating tubes first passes and then over the heating tubes comprising the battery 6 through which the oil supplied to the two batteries of heating tubes last passes, and these heating gases then pass generally downwardly through the heating flue 7 over the heating tubes comprising the two batteries 5 and G to the stack fiue 10.

tubes illustrated in Fig. the heating gases similarly pass first over the heating tubes comprising the battery through which the oil supplied to,v the two batteries of heating tubes first passes and then over the heating tubes comprising the battery through which the oil supplied to the two batteries of heating tubes last passes. The order of oil ow through theV several banks of heating tubes comprising the battery of heating tubes through which the oil rst passes, battery 5a in Fig. 3, is reversed as compared to the order of oil flow through the banks of heating tubes comprising the battery 5 in Fig. 2. Corresponding parts ,are designated by the same reference characters in Figs. 2 and 3.

In the modified arrangement of heatingv As thehot oil products discharged through connection 12 pass the p ressure reducing valve 3, the pressure thereon is reduced from a pressure of several hundred pounds per square inch to a pressure approximating atmospheric pressure for example. In -the vapor separating receptacle 4, a vaporized fraction is' separated from an unvaporized fraction. The vapors comprising the vaporized fraction are taken oif through connection 13 and are subjected to a reliuxing operation n reflux tower 14 from which the vapors remaining uncondensed escape through connection 15 to a condenser 16 arran ed to discharge into a receiver 17 from w ich a condensed distillate product is discharged through connection 18 and uncondensed vapors and gases through connection 19. AA superatmospheric pressure, lower however than the pressure under which the hot oil products are discharged from the second battery of heating tubes, may be maintained in the vapor separating receptacle 4 and the reflux tower 14 and regulated by means of valve 20, or by means of suitable valves arranged beyond the condenser or receiver. Raw oil or sonie other reliuxing medium is supplied to the reiiuxing operation through connection 21 by means ofpump 22, and utilized therein as a direct reiuxing medium for effecting and controlling the operation. Reiiux condensate, or admixed reflux condensate and raw oil, is supplied to the batteries of heating tubes arranged in the heating furnace 1 from the reiluxing operation through connections 23 and 11 by means of pump 2. Raw oil, or additional raw oil, may

-also be supplied to the vapor separating receptacle through connection 24. Residual oi the unvaporized fraction separated in the vapor separating receptacle, is discharged from the vapor separating receptacle 4 through connection 25.

In initiating operation, oil, supplied through connection 24,l is circulated from the vapor separating receptacle 4, b means of valved connection 26, through tlie batteries of heating tubes and back to the vapor separating receptacle until normal operating conditions of temperature and pressure are reached, the valve in connection 26 being closed during normal operation. The supply' of oil through connection 24 may or may not be continued during normal operation. Connection27, communicating through valved branches with the lower ends of each of the heating tubes, is provided for pum ing out the battery of heating tubes at t e end`of a run. The vapor separating receptacle 4 is pumped out at the end of a' run through connection 28.

In carrying out the invention -in the apparatus illustrated, vapors may be taken olf from the vapor separating receptacle 4 under a pressure in the general range of 1-10 pounds per square inch or under a somewhat higher pressure, for example, and the oil forced through the batteries of heating tubes may be heated therein to a temperature approximating 900950 F., as discharged therefrom, under a pressure in the general range of 300-600 pounds per square inch, as discharged therefrom, for example. The rate at which raw oil, or other refluxing medium, is supplied through connection 2l may be regulated to condense in the refluxing operation all constituents higher boiling than suitable Aas components of the desired distillate product, and residual oil may be discharged through connection 25 at a rate regulated to maintain a uniform liquid level in the vapor separating receptacle 4. Cool raw oil may be supplied through connection 24, during normal operation, to arrest the cracking` reaction initiated in the batteries of heating tubes.

In the apparatus illustrated, the vapor separating receptacle 4, the reflux tower 14 and connections l2 13, 23 and 11 are with advantage thoroughly lagged or thermally insulated.

The heating furnace 1 may, with advantage, be arranged and operated as described in Letters Patent Nos. 1,574,546 and 1,574,547 issued to Sinclair Reiining Company, Februar 23, 1926, on application of thelate John E. Bell o`r as described in Letters Patent No. 1,623,778 issued to Sinclair Refining Company, April 5, 1927, on application of the late John E. Bell.

The present invention has a number of advantages. The combination of vertical oil flow and high velocity oil flow in the heating operation minimizes any tendency toward deposition of pitch or carbon in the heating tubes. The arrangement of the heating tubes is peculiarly'compact and permits theuse of a gang cleaner with maximum advantage. The heat exchange relations between the heating gases and the oil being heated to a cracking temperature, provided by this invention, are peculiarly effective in so-called pressure coil cracking operations.

lVe claim:

In the manufacture of lower boiling hy- 'drocarbon oils from higher boiling hydrocarbon oils, the improvement which comprises forcing a stream of high boiling oil successively through two batteries of series connected vertical heating tubes arranged in oil lajsi: passes and then passing the heating gases generally downwardly through Said heating flue in heat exchanging felation Willi the oil in said batteiies of heating tubes, anal thereby heating the oil to a cracking tempera- -'ture, maintaining a superalmospheric p'essure on the oilin-salfl batteries of heatlng tubes and taking off vapors including Vapoxs of the desired low boiling oil from saicl'vapor separating receptacle under reduced pressui'e.

1 ln testimony Wheieof We ax our signa-a tures.

' EDWARD W. lSUM.

EUGENE C. HER'EFHEL? 

